Geometrical instrument



Nov. 25, 1941. H. E. MAUPIN 2,253,637

l GEOMETRICAL INSTRUMENT Filed Aug. 9, r1941 HENRY M4 upf/v "MMA/d Mraz/veil Patented Nov. 25, 1941 UNITED STATES PATENT voI-FlcE GEoME'rmcAr. ms'rnUMEN'r Henry E. Maupin, Dayton, Ohio Application August 9. 1941, serial No. 406,234

(ci. 'na-e9) (Granted under the act of March 3. 1883, as

amended April 30, 1928; 370 0. G. 157) 3 Claims.

The invention described herein may be manufactored and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to geometrical instruments and more particularly to rotary cutters. This invention has as its objects the provision of a geometrical instrument that is extremely*- rugged, one that. may bel accurately adjusted to mark or cut a hole of a given diameter, one that has a wide range of adjustment characterized by the feature that the marker or cutter may be -moved to a position very close to the pilot drill,

said side walls. The body member is adjustable with respect to the U-shapedsweep member in order that the pilot drill may be positioned at any distance from the cutter bit within the range of operation of the device. When it is desired to `use the tool in a given position, the U-shaped sweep bars are forced downward to exert great pressure on the inner side Walls of the body member and this holds the sweep member securely in place.

In the drawing, Figure 1 is a perspective View of my instrument. Figure 2 is a vertical sectional view taken through the center of the pilot drill and transverse to the bars of the elongated U-shaped sweep member whereas Figure 3 is a vertical sectional View taken through the center of the pilot drill and'in a plane parallel to the bars ofthe elongated U-shaped sweep member.

vFigure 4 illustrates in perspective certain details of the means that holds the pilot drill as well as forces the bars against the body member. Figure 5 is a bottom viewvof the device o f my invention showing graduated scales that enable an accurate setting of my instrument to be made.

In the drawing there is shown a U-shaped sweep member I6 with a cutter bit I0 at the closed end thereof. The cutter bit I0 may be used for cutting a hole or merely marking a circular line of a given diameter and may be replaced by any other form of cutting and/or marking tool, for example'a pencil, without departing from the broadest aspects .of this invention. The cutter bit III is held rigidly in place by asuitable lock screw Il, and may befreadily replaced without affecting the adjustment of the instrument. The outer side walls of the two parallel bars. that comprise the U-shaped sweep I6, are tapered at an angle of about fifteen degrees from the vertical throughout their respective lengths. The inner walls of the elongated bars I6 are, however, parallel as well as vertical. A body member II has inner walls tapered at an angle conforming to the taper of the outer side walls oi member I6 and in contact therewith. The body member Il has rigidly attached thereto a chucking shank 2l having an internal left hand thread. A cylindrical member I9 has a iiange thereof I5 together with another cylindrical portion 20.

The flange I5 and the portion 20 nt into a cavity in the body member II and the pilot drill I8 extends through the centrically located hole -in cylindrical member I9 and is fastened to that member by the pilot drill lock screw- Il. Located above the member 20 is a knurled adjusting member I3 which is rigidly fastened to the left hand threaded screw I2 so that when the knurled member I3 is turned manually agreat-pressure is exerted downwardly on the portion 2li and hence upon the flange I5. This orcesthe ange I5 against the bars I6 and causes these bars'to contact their complementary surfaces of body Il under great pressure. To move the pilot drill I8 with respect 00 the cutter bit I0, it is simply necessary to loosen the knurled member I3 and then move the bars I6 in one direction or the other to the desired new position which may be determined by reference to the graduated scales 22 and 23 shown in Figure 5. When the new setting has-been accurately determined by reference to the scales, the knurled member I3 may again be tightened to lock the device in its desired position.

The scales 22 and 23 may be graduated in any suitable increments that will eifect a vernier adjustment, for example the scale 22 may have a graduation mark every 1/40 of an inch andthe scale 23 may have graduation marks every ts of aninch each side of the zero mark thereof.

To use my invention, the knurled member I3 is loosened and the slidable bars I6 moved in or out ofbody member II until the scales show the desired size of hole will becut by the device. The pilot drill I3 is then positioned on the work piece at a point where it is desired to have the center of the hole to be cut. 'I'he chuck of a brace is clamped over the portion 2| of housing Il and the entire device, including the pilot drill Il and the cutter bit I is rotated by the brace. 'I'he cutter bit then cuts a hole in the work piece 2l. Due to the rigid support for the cutting tool I0, the vibrations and usual chatters of the tool are almost completely eliminated and this preventsthe so-lcalled digging-in of the cutter bit l0. The cutter bit i0 rotates smoothly and in synchronism with the pilot drill I8 until it flnally cuts a slot completely through the work piece 24. Hence it is possible to not only obtain a quick accurate adjustment of my instrument before beginning to cut a hole but it is possible to cut the hole with great speed and accuracy due to the absence of chatter.

I claim to have invented:

1. A rotary cutter tool comprising a body member having a base and dening a slot therethrough of uniform cross-section throughout the length thereof; said slot having a narrow portion of its cross-section at the base of the body member and said slot having straight sides tapering awayv from each other as the distance from said base increases; an elongated U-shaped sweep member located so the plane of the U is parallel to the base of the body member; said U-shaped sweep having outer side walls that t to and conform in taper with the said tapering walls of said slot; said U-shaped sweep having a top surface located in a plane parallel to said base and a bottom near said base; a drill carrying member fitting snugly between the bars of said U-shaped sweep and having a flange located on said top surface; a pilot drill carried by said member, having a supporting portion located in said member near the flange, and a drill portion extending outwardly from the supporting portion and past the plane of said base; means attached to said body member to control the position of said drill carrying member and retain 4the same in fixed relation with the body member; a tube extending above the body member, in xed relation thereto and having threads on the inside of the tube; means for exerting a force on said ange comprising a threaded rotatable screw member operatively cooperating with said threads inside said tube and operable to be rotated to exert great pressure downwardly and force said flange in contact with said top' surface, whereby said screw member may also be rotated to release said pressure and enable adjustment of the device, and a cutter bit mounted at the closed end of said U-shaped sweep member and projecting therefrom in a plane parallel to the pilot drill and in the same direction as the pilot drill projects from said drill carrying member.

2. A geometrical instrument comprising a body member having an internal slot the sides of which relatively taper away from each other as the distance from one surface of the member increases; a second member positioned in said slot and having side walls conforming to the -taper and shape of the sides of said slot; means to engage the article to be worked comprising a pilot to act as a centering tool of the instrument and located in fixed relation to one of said members and extending away from said surface with its pivot point located in the direction away from said surface that planes of the tapering sides converge, and a marker attached to the other of said members and extending therefrom parallel to the pilot; and manually controlled means located on said body member operable to move into contact with said second member and exert a large compression on the same to force the same towardsaid surface, whereby, to clamp said members together; said manually controlled means also being operable to release the large force between said members, whereby they may be moved relative each other to eilect various distances of separation between said pilot and said marker.

3. A geometrical instrument comprising first and second members one of which passes through the other; the outside member having its inner side walls relatively tapered and the inside member having its outer side walls substantially similarly tapered; means cooperating with said members operable to either-force said tapered surfaces in contact under great pressure, and thereby hold the same in fixed relation to each other,

or to release the pressure therebetween, whereby to permit the members to be moved relative to each other; a pilot carried by the iirst member;

and a marker carried by the second member.

HENRY E. MAUPIN. 

